We tried to get reservations to Mammoth on Friday (see earlier thread) but they were all sold out, so I ended up going to this cave instead. I asked the guide about speleothems before going in. She asked what those were. I said cave formations. She replied that this was a very special cave, it was a river cave and had no cave formations. If I had known that I would have tried to find some other cave. But I saw huge machinery ("we don't have stalactites or stalagmites, we have stalacpipes.") and it was better than nothing.http://hiddenrivercave.com/